relax SVN archive

Converted the pymol_control user function to the auto-generation design.

For this process, the pymol.macro_apply and pymol.macro_write user function colour_start and
colour_end args had to be split. They previously accepted both a Molmol or X11 colour name or an
RGB colour array. Now there are separate args for the colour name and RGB colour array.

The Sequence based wizard page GUI elements now return None if the field is empty.

This was previously returning [] or () to the auto-generated user functions when they were expecting
None.

The auto-generated user function menu is now correctly sorted.

Converted the model_selection user function to the auto-generation design.

Added graphics for the model_selection user function.

Created icons and wizard graphics for the calc and minimise user functions.

Fix for the Angles.test_angles system test.

The user function angle_diff_tensor now has a user function class and is called angles.diff_tensor.

Fixes for the standardisation of the max_iter keyword arg in the minimise user function.

Created icons for the grid_search user function.

Eliminated the wiz_combo_default and combo_default args from the GUI auto-generated user functions.

These are now provided by the 'default' arg.